POWER SPECTRAL ANALYSIS OF RESIDUAL AEROMAGNETIC MAP OF SOKOTO BASIN, NORTH WESTERN NIGERIA

Abstract

Aeromagnetic data obtained from a recent aeromagnetic survey of Sokoto Basin, northwestern Nigeria has been studied using Power Spectral (PS) analysis. The Sokoto Basin is an arm of the Iullemmeden Basin is situated between latitudes 10°30’’ N to 14° 00" N and longitudes 3° 30” E to 7° 00" E in the Nigeria national grid. The PS analysis was carried out to determine the depth to magnetic sources in the Basin. By splitting the study area into 16 spectral model blocks, the spectral probe of 27.5 by 27.5 km2 for each block was carried out respectively. The results of the PS analysis revealed two prominent magnetic source depth layers. Depths determination of the magnetic sources showed that the first layer has average depth of 0.28 km which is interpreted as shallow magnetic zones attributed to the intrusions of magnetic rocks into the sedimentary formation. The second layer has average depth of 1.86 km and was interpreted as the deep magnetic source representing the depth to magnetic basement. Hence the results show that the maximum thickness of the sedimentary layers to be 1.86 km is the limit of the depressions on the basement surface of the basin. Hence it suggests that exploration of hydrocarbon which would require a minimum sedimentary thickness of about 2.3 km as obtainable in the coasts of West Africa region is also not feasible.